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granins


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A family of related acidic proteins (chromogranins, secretogranins, 400–600 aa) found in many endocrine cell secretory vesicles where they may have a role in granulogenesis and packaging, and are the source of several physiologically active peptide fragments. Chromogranin A (parathyroid secretory protein) is stored and coreleased with catecholamines and parathyroid hormone from storage granules in the adrenal medulla and the parathyroid gland respectively. Chromogranin B (secretogranin 1) was initially characterized in a rat pheochromocytoma cell line. Chromogranin C (secretogranin II) was originally described in the anterior pituitary. Four other members of the family, secretogranins III, IV, V and VI are known although the role of secretogranins III and IV are unclear. Secretogranin V (pituitary polypeptide 7B2; secretory granule neuroendocrine protein-1; 212 aa) is a specific chaperone for prohormone convertase-2. Secretogranin VI is the α subunit of the stimulatory trimeric G protein, Gs, and mutations are associated with a range of disorders such as Albright hereditary osteodystrophy, McCune-Albright syndrome, and pseudohypoparathyroidism Ib, as well being mutated in various pituitary tumours. Peptides derived from chromogranins (e.g. pancreastatin; vasostatins) have autocrine, paracrine, and endocrine activities.

Subjects: Medicine and Health.


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